﻿// bsn ModuleStore database versioning
// -----------------------------------
// 
// Copyright 2010 by Arsène von Wyss - avw@gmx.ch
// 
// Development has been supported by Sirius Technologies AG, Basel
// 
// Source:
// 
// https://bsn-modulestore.googlecode.com/hg/
// 
// License:
// 
// The library is distributed under the GNU Lesser General Public License:
// http://www.gnu.org/licenses/lgpl.html
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Diagnostics;

namespace bsn.ModuleStore.Sql.Script {
	public abstract class ExpressionCase<T>: Expression where T: SqlComputable {
		private readonly Expression elseExpression;
		private readonly List<CaseWhen<T>> whenItems;

		protected ExpressionCase(Sequence<CaseWhen<T>> whenItems, Expression elseExpression) {
			Debug.Assert(whenItems != null);
			this.whenItems = whenItems.ToList();
			this.elseExpression = elseExpression;
		}

		public Expression ElseExpression {
			get {
				return elseExpression;
			}
		}

		public IEnumerable<CaseWhen<T>> WhenItems {
			get {
				return whenItems;
			}
		}

		public override void WriteTo(SqlWriter writer) {
			WriteCommentsTo(writer);
			writer.WriteScriptSequence(whenItems, WhitespacePadding.NewlineBefore, null);
			if (elseExpression != null) {
				writer.WriteLine();
				writer.WriteKeyword("ELSE ");
				using (writer.Indent()) {
					writer.WriteScript(elseExpression, WhitespacePadding.None);
				}
			}
			writer.WriteLine();
			writer.WriteKeyword("END");
		}
	}
}
